So the System Cooldown between any two EPtX of the same time is as long as the power buff, equaling infinite uptime?

Is the Global Cooldown between two different EPtX (such as EPtS and EPtW) still 15 seconds or is it 10 seconds? If it's still 15, then cruisers which run 2 different pairs won't infinite uptime (and lets face it, Cruisers with 6 or 7 Engy Slots don't have much else useful to run).